Treatment of impure molten metal and metallic masses



Patented 13, 1926.

UNITED STATES KERRY HARRIS, OF LONDON, ENGLAND.

PATENT. OFFICE.

TREATMENT or nnumn MoLTEn MEIAL am) KETALLIC MASSES.

No Drawing.

To all whom it may concern:

Be it known that 1, Henry HARRIS, a subect of the King of Great Britain, and resident of -London, England, have invented certain new and useful Improvements in Treatment of Impure Molten Metal and Metallic 'Masses,,of which the following is a specification.

My invention relatesto the treatment of impure molten metal and molten metallic masses, and more particularly to the treatment of impure molten lead Land othermetallic masses containing one or more alloying ingredients, such for example, as arsenic and/or tin with or without antimony. The

invention isespecially useful for the simultaneous treatment of molten lead containing alloying ingredients and of aspent reagent containing a lead alloying ingredient derived from a previous lead treatment.

It is known according to previous inventions of mine, how totreat molten lead with a reagent comprising caustic alkali, preferablymixed with sodium chloride, and utilizing a suitable oxidizer, to separate from the molten lead various alloying in redients (my copending application Serial ,0. .698,- 279, filed ,March 10, 1924, and application Serial No. 724,899, filed July 8, 1924, both for refining lead), The alloying ingredients, according to the known inventions, may be removed together or .fractionally.

In my last said application I have described a process whereby the alloying ingredients arsenic, tin and antimony. may be very' effectively removed togetheror fract-ionally by bringing the molten lead containing the alloying ingredients into intimate, contact with a molten reagent mixture of caustic sodaand sodium chloride to which is gradually added a limitedquantity of a suitable oxidizer such for example as sodium nitrate.

According to said process, the amounts of the reagent ingredients and of the oxidizer, and the duration of the treatment of the molten metal for each batch of reagent is so proportioned that said alloying ingredients may be substantially. 'fractionallyremoved so that the arsenic is eliminated substansubstantially free of the antimony,

tially free of tin, thetin being eliminated the antimony is eliminated. The lead and reagent. mix are preferably broughtv into intimate'contact by circulating the lead in distributed or sprayed form while maintained at a temperature not exceeding. about and then Application filed Depember 11, 1924.- Sex-31110. 755,160.

500 C. through the reagent mixture until one of the alloying ingredients, for example, arsenic, is removed perhaps with a little tin, then circulating the lead through an- ,other batch of reagent until tin is removed perhaps with a little antimony, and then circulating the lead through another-batch of reagent until the antimonyis totally removed; the arsenic, tin and antimony ingredients being found in the spent reagent mixes in the form of theiraoxysalts1,e., sodium oxysalt of arsenic, sodium oxysalt of tin and sodium oxysalt of antimony; or if desired, the. arsenic, tin and antimony may be removed together by one operation; or,

the arsenic and tin with a little antimony may be removed first, then the rest of the antimony may be removed by a subsequent batch of reagent.

While said process is quite .efiicient in separating said impurities or alloyingdrigradients from the lead, and more'efiicient or economical than any other known process,

yet a considerable amount of commercial oxidizer is used which is an item ofexpense.

Furthermore, the resulting spent reagents containing caustic soda and an alkali \ox salt of an alloying ingredient have to e treated to recover the caustic alkali for sub sequent use, and also to recover thealloyiiig ingredient, the oxygen being lost. It is also a fact that therev is a wider market for some lead alloys than for others. For example, there is a better market for antimoniallead than for "a tin-antimony lead alloy. Furthermore, the conversion of the oxysalt of antimony tometallic antimony involves con- 1 siderab'le expense, and the partial or total loss of the alkali with which it has been combined. "w The objects of the present invention are to reduce the cost of-the treatment ofthe impure lead or other suitable metallic loying ingredient which forms an alloy'for 4 same time eliminating from the lead an undesirable alloying ingredient.

Further objects and advantages of the invention will more fully appear from the following description of certain preferred ways of practicing the invention. a The invention conslsts 1n the novel process which is hereinafter described, by way of example, accordingito said preferred ways of practicing the same, and in the novel features or steps of the process. The invention will be more particularly pointed out in the appended claims,

According to one aspect of this invention, advantage is taken of the underlying principle that certain alloying ingredients, such for example as arsenic, tin and antimony, may be, at least to 'a large extent, preferentially or fractionally oxidized out of molten lead and other molten metallic masses, to enable the utilization of a spent reagent containing an alkali oxysalt of one or more of said alloying ingredients as an oxidizer in the treatment of molten lead and other suitable metallic masses. For example, if molten lead containing tin and antimony is to be treated by the. use of caustic soda, inasmuch as the antimony has less aflinityfor the oxygen of the oxysalt in the reagent mix than has the tin, if we use in the reagent mix, oxysalt of antimony in the presence of free caustic soda, the antimony will be reduced to metallic antimony which will join any antimony in the lead (or if no antimony is present in thelead the antimony of the oxysalt will join the lead), the oxygen of the oxysalt combiningwith the more readily oxidizable alloying ingredient,-

tin, to oxidize the tin and thus separate it from the lead in the form of 1ts alkali oxysalt. Therefore, a spent reagent containing an alkali oxysalt of antimony may be used as an oxidize-r for the treatment of lead for the separation of the tin, thus reducing the amount of commercial oxidizer to be added in such treatment. J V For example, in utilizing sodium antimoniate as an oxidizer for removing tin from lead, the following equation shows the reaction that is believed to take place:

From this equation it will be seen that if 480 parts by weight of antimony contained.

' with the lead from which the tin has been removed by oxidation.

Similarly, in utilizing sodium antimoniate probable reactions taking as an oxidizer for removing arsenic from lead, the following equation will show the reaction which is believed to take place:

alloyed with the lead from which the arsenic has been removed.

Similarly again, in using an alkali oxysalt of tin contained in a caustic alkali mixture for removing arsenic from lead, the following formula is believed to represent the re-. actions:

According to this formula, weight of tin contained in its oxysalt in suspension in caustic soda will remove substantially 300 parts by weight of arsenic from molten lead containing arsenic, in

which case 593 parts of tin in metallic form will become alloyed with the lead and replace the arsenic in the lead, and at the same time the arsenic in the form of its alkaline oxysalt will replace in the alkaline mixture the alkali oxysalt of tin. In the treatment, by this invention, of impure metallic masses of low melting point, such for example as the treatment of impure lead, the molten metallic mass as pointed out in my above-mentioned copending appli- 593 parts by a cations, is preferably maintained "at a tem- 'perature not exceeding about 500 C.

While these are given as examples of the place wherecaustic alkali and in particular caustic soda is used, it will be understood by those skilled in the art that these exact amounts will vary under different practical conditions. It will be further understood that in any case'if there are two alloying ingredientsto be removed from-the lead, a different computation for the oxidizer must be made, and that in any case some other oxidizing agent may be used along with the alkali oxysalt 2f a 'lead alloying ingredient to get the proper stoichiometric requirements for the reactions.

Besides reducing the amount of commercial oxidizer required, it is possible to thus utilize the total alkali of the spent reagent for the further treatment of .lead without having first to recover it from the. spent reagent. Another advantage is that it is not necessary to otherwise treat the particular spent reagent containing the oxysalt of antimony for tion of the arsenic and/or tin.

The invention is useful in such acase regardless of whether the antimony is to bev finally removed from the lead or left in the lead as antimonial lead. For example, if we use a caustic alkalireagent containing the alkali oxysalts of arsenic, tin and antimony for the, treatment of lead containing served).

arsenic, tin and antimony, the antimony pf the reagent will go to join the antlmon 1n the lead and cause the arsenic and tin o the lead to separate out in the form of their oxysalts (assuming always, of course, that the stoichiometric requirements are ob- The resulting spent reagent will thus have only the oxysalt of arsenic and tin, the antimony having ,gone to the lead. It now it is desired toremove the antimony from the lead, the lead will ,be treated in known manner for this'purpose.

In the same manner a spent reagent containing an alkali oxysalt of tin may be utilized as" an oxidizer for separation of arsenic from the lead in the form of its oxysalt; or the oxysalt ofantifnony may 'be thus used to separate from lead both arsenic and tin in the form of their oxysalts; or-the alkali oxysalts of antimony and tin may be used to separate the arsenic from the lead. v a 1 The process holds good for the use of the oxysaltof any alloying ingredient of the. lead, as an. oxidizer, to separate from the lead any other alloying ingredient or ingredients which have a greater afiinity for the oxygen of said oxysalt than has the alloying ingredient of said oxysalt. f

" Such an alkali oxysalt of the alloying ingredient' may be used alone as the oxidizer or in conjunction-with some other oxidizing agent suc for-example as sodium nitrate, according o the amount and composition of said oxysalt on hand, and the quantity and nature of the alloying ingred' nt of the lead to be treated. I v v 1 As heretofore, v of caustic soda and sod liloride' as the reagent, because, amoqfia other advantages,

I' prefer use a mixturethe; sodium chloride ren rs-the reagent mix more effective as a car :er of alkaline oxy-' salts. 5 15:; In carrying out the process, any'suitable apparatus may be used, but I prefer to use apparatus such as";shown '-and my United States Patent 'No:' -"'1,4fi5,12 8,

, ing application an alkali oxysalt 'ried out Lin difl'erent ways Letters Patent, is: h

1 Method of treatinga molten metallic. mass containing two or more 1 metallic in gredients, for the separation from the mass ,oflone or more of the same by the-use are e 14, 1923, forapparatus for or as shown in my copend- Serial No.'605,597,'filed December 8, 1922, for apparatus for refining or separating metals.

Accordin to another aspect of my invention, if. it Is desired to treat some molten metallic mass other than impure lead, conta ning alloying ingredients such for, example as those above mentioned,to separate granted August refining metals,

one or more of same, as for example to separate arsenic from molten allo of tin and arsenic, this can be done by ringing the molten alloy into intimate contact with loy being replacing oxidizedand the tin of the oxysalt the arsenic in the alloy. As was of tin, the arsenic of the alabove pointed out in the case of treating impure lead, the replacement of arsenic in the alloy by tin 1s dueto the fact, that tin has less afiimty for the'oxygen of the oxysalt in the mixture than has the arsenic; and likewise, as above stated with respect to the treatment .of impure lead or lead alloy, the process holds good for the use 6f the oxysalt of any metal which will combine with the molten metallic mass, as an oxidizer to separate from said metallic mass containing other gen of said oxysalt oxidizer than has t oxysalt oxidizer.

I am aware that in the strictest sense arsenic is not generally speaking, and I use the words metal and metallic ingredients herein, in the broader and more general sense, and as including metalloidal substances such as arsenic. While I have described the invention according to certainpreferred ways' of carrying out the same, 1t will be understood by those skilled in the art after understanding. my invention, that the invention may be carchanges and scope'of the invention, and I do not wish to be understood as being limited inthepractice of the invention other than as set fort-h in the'appended claims.

- Havin thus described my invention, what I c aim as new foritsboznb'ined oxygen than hasthe one or e metal of said considered as a'metal but in metallurgynt is often designated asa metal and that various modlficataons may, be made therein without departing from the spirit'or and desire to secure by v i '120 .metallicsingr'edients, such of them as have a greater alfinity for the oil ie nt containing an oxidizer, character-. are thereby that as an oxidizerthere is addedox alt of one. or more metals which i 2. Method of treating a molten metallic p of one or more of the same by the use of a.

ized thereby that there is added as an o xi- 'dizer, oxysalt of one or more metals which more of said metallic-ingredients to be removed from the metallic mass.

mass containing two or more metallic ingredients, for the separation, from the mass reagent comprising caustic soda, characterwill combine with the metallic mass and which whilst in the mixture, has less afiinity for its combined oxygen than has the one or more of said metallic-ingredients to be removed from the metallic mass.

3. Method of treating a molten metallic mass containing two or more metallic ingredients, for the substitution in the mass of one or more desirable metals for one or more of said metallic ingredients, 'which comprises bringing into intimate contact said molten metallic mass and a rea ent comprising free caustic alkali, to Whic is added as an oxidizer, oxysalt of one or more desirable metals alloyable with the metallicingredient or ingredients not to be. removed from the metallic mass, said metal of the oxidizer whilst in suspension in the mixture having less aflinity for its combined oxygen than has the one or moreof said metallic ingredients to be removed from the mass. 4. Method of treating a molten metallic v mass containing one or more of the metallic f suspension in the mixture has less aflinity for" I idients alloyed ingredients arsenic, tin and antimony, for

separation from the metallic mass of one or more of said metallic ingredients, WlllCll com prises bringing into intimate contact s a1d molten metallic mass, a reagent comprismg caustic soda, and oxysalt of one or more of said metallic ingredients which last metallic ingredient or ingredients wh1lst 1n the mixture has less affinity for its combined oxygen than has the one or more other of said metallic ingredients to be removed from the mass.

55. Method of treating a molten metall c mass containing one or more of the metallic ingredients arsenic, tin and antunony for separation from the metalllc mass of one or more of said metallic ingredients, whlch comprises bringing into intimate contactn the presence of free caustic alkah, said molten metallic mass and oxysalt of one or more at said metallic ingredients WhIeh last metallic ingredient or ingredientswhllst n its combined oxygen than has the one or more other of said metallic ingredients to be removed from thema'ss.

6. Method of treating molten lead for separation therefrom of one or more ingretherewith, which ,cornprises using as an oxidizer for one or moreof the alloying ingredients an alkali oxysalt of a difierent lead alloying ingredient from the one or ones to be removed.

7. Method of treating molten lead for separation therefrom of one or more ingredients alloyed therewith, which comprises bringing into intimate contact the molten lead and a mixture containing free caustic alkali and an oxysalt of another lead alloying ingredient which will effect the elimination from the lead of said first alloying ingredient or ingredients.

8. Method of treating molten lead for separation therefrom of one or more ingre clients alloyed therewith, which comprises br nging into intimate contact the molten lead and a reagent containing caustic alkali ients alloyed therewith, which "comprises bringing into intimate contact the molten lead and a reagent comprising caustic soda and an oxysalt of a lead alloying ingredient which Whilst in the mixture has less afiinity for its combined oxygen than has the alloydients alloyed therewith, which comprises .bringin the molten lead into intimate conalloying ingredient. or ingredients to be removed fromthe lead.

12. Method of treating molten lead for separation therefrom of one or more ingredients alloyed therewith, which comprises bringing the molten leadwhile maintained at a .temperature not exceedingabout 500 G. into intimatecontact with a molten re agent comprising molten caustic alkali, and gradually'adding' as an oxidizing agent an alkali oxysalt of a lead alloying ingredient,

which last alloying ingredient. Whilst in-the mixture has less afiinity for its combined oxygen than has the alloying ingredient or ingredients to be removed from the lead.

13. Method of treating molten lead for oxysalt of an alloy ing ingredient to be removed from the lead.

10. Method of treating molten lead for separation therefrom of one or more ingre-v the separation of an ingredient alloyed therewith, which comprises separating said alloying ingredient in the form of its oxysalt by treating the molten metal with caustic alkali and an oxidizer comprising an oxysalt of a lead alloying ingredient not so readily separable from the molten lead as is the alloying ingredient to be removed.

14. Method of treating: molten lead for the separation therefrom of one or more ingredients alloyed therewith, which comprises treating the molten lead with a reagent comprising caustic alkali and a suitable oxidizer whereby a mixture comprising caustic alkali and one or more oxysalts of said alloying ingredients are derived, and using said derived mixture as an oxidizer in the treatment of a further batch of lead for the removal therefrom of a lead alloying Zingredient having greater aflinity for the oxygen ofsaid ox salts in the reagent mixture than has the alloying ingredient of said oxysalt.

15. Method of treating molten lead for the separation therefrom of one or more ingredients alloyed therewith, and of simultaneously treating a mixture comprising caustic alkali and an oxysalt of a lead alloying ingredient derived from the refining of lead, to reduce and separate said alloying, ingredient from said oxysalt and free the alkali for further use, which comprises bringing into intimate contact said molten lead an said mixture containing caustic soda and an alkali oxysalt of an alloying ingredient, which last ingredient whilein the mixture has less aflinity for its combined oxygen than has the alloying ingredient to be removed from the lead, whereby said oxysalt of the mixture will become decomposed, its alloying ingredient going to the lead in metallic form, its oxygen combining with the more readily oxidiz able alloying ingredient of the lead oxidizing said alloying ingredient, and its alkali base combining with-the said oxidized alloying ingredient.

16. Method of treating molten lead-for the separation therefrom of an undesired alloying ingredient and for the enriching of the lead with another alloying ingredient, which comprises bringing into mtimate contact the molten lead containing the undesired alloying ingredient, free causticalkali and 7 an oxysalt of anenriching alloying ingredi ent, which ingredient whilst in the mix-' ture has less afiinity for'its combined oxygen than has the undesired alloying ingredient. 17. Method of separating arsenic from a molten arsenic tin alloy, which comprises bringing said alloy into intimate contact with a reagent containing an alkali oxys'alt of tin.

In testimony name to this specification.

' HENRY HARRIS.

whereof I have signed my 

